func main() {
    var s = "ABC123あいう";

    print(s);
    print("s.length = " + s.length);
    print("s.substring(0, 0) = " + s->substring(0, 0));
    print("s.substring(0, 1) = " + s->substring(0, 1));
    print("s.substring(0, 2) = " + s->substring(0, 2));
    print("s.substring(0, 3) = " + s->substring(0, 3));
    print("s.substring(0, 4) = " + s->substring(0, 4));
    print("s.substring(0, 5) = " + s->substring(0, 5));
    print("s.substring(0, 6) = " + s->substring(0, 6));
    print("s.substring(0, 7) = " + s->substring(0, 7));
    print("s.substring(0, 8) = " + s->substring(0, 8));
    print("s.substring(0, 9) = " + s->substring(0, 9));
    print("s.substring(0, 10) = " + s->substring(0, 10));
    print("s.substring(0, -1) = " + s->substring(0, -1));

    print("s.substring(1, 0) = " + s->substring(1, 0));
    print("s.substring(1, 1) = " + s->substring(1, 1));
    print("s.substring(1, 2) = " + s->substring(1, 2));
    print("s.substring(1, 3) = " + s->substring(1, 3));
    print("s.substring(1, 4) = " + s->substring(1, 4));
    print("s.substring(1, 5) = " + s->substring(1, 5));
    print("s.substring(1, 6) = " + s->substring(1, 6));
    print("s.substring(1, 7) = " + s->substring(1, 7));
    print("s.substring(1, 8) = " + s->substring(1, 8));
    print("s.substring(1, 9) = " + s->substring(1, 9));
    print("s.substring(1, 10) = " + s->substring(1, 10));
    print("s.substring(1, -1) = " + s->substring(1, -1));

    print("s.substring(8, 0) = " + s->substring(8, 0));
    print("s.substring(8, 1) = " + s->substring(8, 1));

    print("s.substring(9, 0) = " + s->substring(9, 0));
    print("s.substring(9, 1) = " + s->substring(9, 1));
}
